Up limits on alias model tris and vertices

[4LT]

Doubles the limit on alias model triangles, and doubles the limit on alias model vertices (to nearest power of 2).

Resolves #352

[andrei-drexler]

@sezero @j0zzz I think ideally these limits would be increased in QS and JoeQuake as well, to avoid incompatibilities between engines.

[4LT]

To be quite honest, I don't know why there's a per-model vertex and triangle limit, seems to me there should just be a global limit. Since models are pre-cached as opposed to loaded at runtime, there shouldn't be a negative performance impact from using a growable data structure

Ah, missed the part where MAXALIASTRIS and MAXALIASVERTS are only used for the size of global arrays; in which case it could be replaced with a malloc'd pointer.

[andrei-drexler]

Since it doesn't look like the new limits will be adopted by other engines, I went with a different approach in df8f926 - the triangle/vertex limits are gone, and the code just emits QS compatibility warnings for developers instead. The frame limit is still there for now, though.

[mhQuake]

I don't think the old limits are relevant anyway, other than if compatibility with software Quake and the old meshing code is felt important. Other engines should likewise push to remove them.

This is aside from the frame limit, which is protocol-dependent, of course.